OS C-21 (UNITS 3 & 4)

A semaphore is a shared integer variable __________

• that can not drop below zero.
  

• that can not be more than zero.

• that can not drop below one.

• that can have more than one value.

 Process synchronization is achieved by using______

• Signals

• Semaphores

• System calls

• Kernel mode

In semaphore when the order of processes they are waiting to the removed from the queue is first in first out (FIFO) then it is called as _______semaphore.

• Weak

• Strong

• Binary

• Counting

After 10P operations were completed on the semaphore followed by 15V operations, the resulting value of the semaphore is_________. if current value of semaphore is 15.

•  10

• 15

• 20

• 11

An operating system contains 3 user processes each requires 2 units of resources R. The minimum number of units of R such that no deadlock will ever arise

• 4

• 3

• 5

• 6

When the result of a computation depends on the speed and order of execution of processes involved, then it is said to be ___________

• Deadlock

• Critical section

• Race condition

• Memory leak

Dijkstra’s Bankers algorithm in an operating system solves the problem of ____

• Deadlock Avoidance

• Deadlock Detection

• Mutual Exclusion

• Page replacement

Which of the following approach may be invoked periodically to test for the deadlock?

• Deadlock Avoidance

• Deadlock Prevention

• Deadlock Ignorance.

• Deadlock Detection

The wait-for graph is a deadlock detection algorithm that is applicable when ____

• all resources have a single instance

• all resources have multiple instances

• all resources have a single 7 multiple instances

• all of the mentioned

An edge from process Pi to Pj in a wait for graph indicates that ___________

• Pi is waiting for Pj to leave the system

• Pj is waiting for Pi to release a resource that Pj needs

• Pi is waiting for Pj to release a resource that Pi needs

• Pj is waiting for Pi to leave the system